From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55755) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UsYw8-0005Qn-4H for qemu-devel@nongnu.org; Fri, 28 Jun 2013 09:42:05 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UsYw6-0005G3-Pw for qemu-devel@nongnu.org; Fri, 28 Jun 2013 09:42:04 -0400 Received: from goliath.siemens.de ([192.35.17.28]:31244) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UsYw6-0005Ff-Fy for qemu-devel@nongnu.org; Fri, 28 Jun 2013 09:42:02 -0400 Message-ID: <51CD92A6.7000309@siemens.com> Date: Fri, 28 Jun 2013 15:41:58 +0200 From: Jan Kiszka MIME-Version: 1.0 References: <1372158807-19715-1-git-send-email-pbonzini@redhat.com> <1372158807-19715-8-git-send-email-pbonzini@redhat.com> In-Reply-To: <1372158807-19715-8-git-send-email-pbonzini@redhat.com> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 07/11] exec: add a reference to the region returned by address_space_translate List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: peter.maydell@linaro.org, qemu-devel@nongnu.org On 2013-06-25 13:13, Paolo Bonzini wrote: > Once address_space_translate will only be protected by RCU, the returned > MemoryRegion can disappear as soon as the RCU read-side critical > section ends. Avoid this by adding a reference to the region, and > dropping it in the caller of address_space_translate. > > Signed-off-by: Paolo Bonzini > --- > exec.c | 16 ++++++++++++++-- > include/exec/memory.h | 3 ++- > 2 files changed, 16 insertions(+), 3 deletions(-) > > diff --git a/exec.c b/exec.c > index 5454e4d..b7f032d 100644 > --- a/exec.c > +++ b/exec.c > @@ -286,6 +286,7 @@ MemoryRegion *address_space_translate(AddressSpace *as, hwaddr addr, > > *plen = len; > *xlat = addr; > + memory_region_ref(mr); > return mr; > } > > @@ -1960,6 +1961,7 @@ bool address_space_rw(AddressSpace *as, hwaddr addr, uint8_t *buf, > memcpy(buf, ptr, l); > } > } > + memory_region_unref(mr); > len -= l; > buf += l; > addr += l; > @@ -2125,8 +2127,10 @@ void *address_space_map(AddressSpace *as, > raddr = memory_region_get_ram_addr(mr) + xlat; > } else { > if (memory_region_get_ram_addr(mr) + xlat != raddr + todo) { > + memory_region_unref(mr); > break; > } > + memory_region_unref(mr); > } > > len -= l; This stage of the implementation looks inconsistent for memory_region_get_ram_addr. Isn't the idea so far that the mr reference is dropped again before leaving the function? > @@ -2226,6 +2230,7 @@ static inline uint32_t ldl_phys_internal(hwaddr addr, > break; > } > } > + memory_region_unref(mr); > return val; > } > > @@ -2285,6 +2290,7 @@ static inline uint64_t ldq_phys_internal(hwaddr addr, > break; > } > } > + memory_region_unref(mr); > return val; > } > > @@ -2352,6 +2358,7 @@ static inline uint32_t lduw_phys_internal(hwaddr addr, > break; > } > } > + memory_region_unref(mr); > return val; > } > > @@ -2399,6 +2406,7 @@ void stl_phys_notdirty(hwaddr addr, uint32_t val) > } > } > } > + memory_region_unref(mr); > } > > /* warning: addr must be aligned */ > @@ -2440,6 +2448,7 @@ static inline void stl_phys_internal(hwaddr addr, uint32_t val, > } > invalidate_and_set_dirty(addr1, 4); > } > + memory_region_unref(mr); > } > > void stl_phys(hwaddr addr, uint32_t val) > @@ -2503,6 +2512,7 @@ static inline void stw_phys_internal(hwaddr addr, uint32_t val, > } > invalidate_and_set_dirty(addr1, 2); > } > + memory_region_unref(mr); > } > > void stw_phys(hwaddr addr, uint32_t val) > @@ -2592,11 +2602,13 @@ bool cpu_physical_memory_is_io(hwaddr phys_addr) > { > MemoryRegion*mr; > hwaddr l = 1; > + bool res; > > mr = address_space_translate(&address_space_memory, > phys_addr, &phys_addr, &l, false); > > - return !(memory_region_is_ram(mr) || > - memory_region_is_romd(mr)); > + res = !(memory_region_is_ram(mr) || memory_region_is_romd(mr)); > + memory_region_unref(mr); > + return res; > } > #endif Unless I'm missing something ATM, address_space_access_valid, cpu_physical_memory_write_rom and tb_invalidate_phys_addr also require unref calls. > diff --git a/include/exec/memory.h b/include/exec/memory.h > index c842d48..2a37b2c 100644 > --- a/include/exec/memory.h > +++ b/include/exec/memory.h > @@ -1003,7 +1003,8 @@ bool address_space_write(AddressSpace *as, hwaddr addr, > bool address_space_read(AddressSpace *as, hwaddr addr, uint8_t *buf, int len); > > /* address_space_translate: translate an address range into an address space > - * into a MemoryRegion and an address range into that section > + * into a MemoryRegion and an address range into that section. Add a reference > + * to that region. > * > * @as: #AddressSpace to be accessed > * @addr: address within that address space > Jan -- Siemens AG, Corporate Technology, CT RTC ITP SES-DE Corporate Competence Center Embedded Linux